Long-term objectives of the research are the explication of the variables of which accommodative hysteresis is a function and to isolate certain visual characteristics of individuals to which accommodative hysteresis may be related. Specific aims include: (1) the relation between the CA/C ratio and the magnitude of accommodative hysteresis, (2) hysteresis magnitude and decay time as a function of the amplitude of accommodation to the fixation target, (3) the influence of hysteresis on the near point and far point of accommodation, (5) the relation between type of refractive error and magnitude of hysteresis effects, (6) hysteresis effects as a function of induction-target contrast and spatial frequency, (7) the role of motion perspective in accommodative hysteresis. The primary method entails determining the refractive state of the eye with a laser optometer modified to make use of the Badal principle. Health related issues arise in connection with the potential role of accommodative hysteresis in clinical refraction and measures of accommodative convergence, accommodative amplitude and range, and estimates of near and far acuity. Hysteresis effects also may play a role in the etiology of myopia and hyperopia.